Impact meter



P 1935- y Y D. D. KNOWLES Y 2,053,436

IMPACT METER Filed Sept. 6, 1950 Patented Sept. 8, 1936 UNITED STATES PATENT OFFICE ILIPACT METER Dewey D. Knowles, Wilkinsburg, Pa., assignor to Westinghouse Electric & Manufacturing Cornpany, a corporation of Pennsylvania Application Septemberfi, 1930, Serial No. 480,147

3 Claims.

' Another object of my invention is to provide impact-measuring apparatus wherein the presence of an impact, of predetermined magnitude,

is' indicated visually. I

A further and more specific object of my invention is to provide apparatus for indicating, at a central station, the magnitude of vibration exist ing at a plurality of predetermined regions of asystem.

A still further specific object of my invention is to provide apparatus for indicating the magnitude of vibration existing in a predetermined region of a system, such as a vehicle, at variedorientationsof the system.

An additional specific object of my invention is to provide apparatus for indicating the magnitude of vibration existing in a predetermined region of a system at predetermined time periods.

Still another object of my invention is to provide a portable impact meter.

An ancillary object of my invention is to provide apparatus for ,detecting' the existence of a fluid pressure of predetermined magnitude.

, Another ancfllary object of my invention is to provide apparatus for detecting continuous and persisting forces of predetermined magnitude.

A further ancillary object of my invention is to provide, in apparatus of the type wherein a gridcontrolled electric discharge tube is utilized, a device for interrupting the discharge -in the tube after it has been initiated. i

40 More concisely stated, it is an object of my invention to provide tractable and portable apparatus for measuring and visually indicating the magnitude of impacts and hence, the extent of vibration of rigid systems.

According to my invention, I provide a mechanical impact-responsive device comprising a mass resiliently supported and capable of moving under' its support under the action of an impact force: 'Themass, under normal circumstances,

closes a contact connecting the control electrode of an electric discharge tube to the cathode of the tube. However, when it moves under the action of an impact, the circuit is opened and the tube is brought to a state of excitation, thus indieating the presence of an impact sumcient to move the particular mass under the action of the particular spring.

The impact which is capable of moving a given mass, is a function of the magnitude of the mass and of the properties of spring supporting it. 5

Hence, by providing a plurality of masses supported on aplurality of springs, the masses and the springs having a variety of properties, impacts of various magnitudes maybe measured. In this manner an impact measuring scale may be 0 provided.

One of the features that is particularly requisite for an impact meter, of the type described herein, is portability. It must moreover, be capable of being operated from a direct-current 15 supply source for, under ordinary circumstances, alternating current is not available on the systems to which the meter is applied.

Moreover, it is a-well known fact that a grid-'- controlled electric discharge tube, when once excited, tends t6 lock itself in and to continue in the state of excitation. Accordingly, I have provided a circuit whereby the tube associated with a certain impact contactor reverts to an unexcited state when the contact is closed; that is, 25 when the impact force has ceased to act on the mass.

The novel features that I consider characteristic of my invention are set forth with par-- ticularity in the appended claims. The invention 30 itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood fromthe following description of a specific embodiment, when read in connection; 35

v with the accompanying drawing, in which:

Figure 1 is a view in side elevation, with the cover opened and part of the side broken away, showing a preferred embodiment of my invention,

Fig, 2 is a plan view of the embodiment of my 40 invention, and

Fig. 3 is a schematic view illustrating the electrical circuit utilized in practicingmy invention.

The apparatus shown in the drawing com- 45 prises a carrying case I wherein are disposed a pluralityof electric discharge tubes 3, (that' -for the preferred practice of my invention,

should be grid-controlled glow tubes), a battery of dry cells 5 for operating the tubes 3, and a 50 plurality of control elements, the characteristics and function of which will be specified hereinafter. i Y

The carrying case I is provided with a plurality of female plugs 'lthrough which which the 55 electric discharge systems. are connected to mechanical impact-responsive devices 9, as shall be explained presently. A single impacter is in- I1 is mounted within the opening I3 on a spring I! of predetermined characteristics, supported on the shoulder -2| formed between the openings l3 and |5. The cylinder I1 is provided with a stem 23 that projects from its lower base 25.

and engages the constricted portion|5 oi the opening. It is thus prevented from tilting as it moves in the distended portion |3 of the opening.

Projecting from the upper base 2'! of the cylindrical mass M is a stub 23 that is adapted to make contact with a second stub 3| supported in a shell 33 of longitudinal T-section, secured in vention is apparent and should be included withimpact indicator 8, represented in the drawing.

. cylinder I points in the system.

the top of the container The--second stub 3| is insulated from the shell 33 of T-section by a dielectric cylinder 35 and is connected to one terminal 31 of the grid-glow tube circuit. The container II is connected to anotherterminal 33 of the grid-glow tube circuit, and the circuit between the two leads 4| and 43 making the connection is closed as long as the cylindrical mass I1 is in its uppermost position.

The contactor 9 is disposed on the object that is under investigation. When the object vibrates under the force or an impact the outer cylinder moves with it and the mass l1 floating on the spring I9 moves with it under the action of the stub 3|. When the outer cylinder I returns to its original position the'spring I9 is compressed and the contact is broken for an instant.

If the relative position of the spring and con-' tacts are interchanged it is apparent that the contact is opened in the initial motion of the There is considerable application for both types of contactors and they should be included within the scope of my invention.

, It is furthermore important to note that while apparatus has been described herein-which operates in the opening of a contactor, apparatus that operates on the closing or a contactor is equally as well operable and may be found use-. ful in certain connections. The application of the contactor that is normally open to myinin its scope.

As has been intimated above, the mechanical should only be regarded as symbolical oi a series oLdevices oi the same. character, each device having such properties as to respond to an impact oi, at least, a predetermined magnitude. These impacters 3 may be disposed, for example, at diiierent points in a system, such as 2. vehicle, and thus provide an indication of the extent or vibration-existing at the particular The impacters may also be disposed in a single regionin a system and thus are adapted to yield an impact-time curve or an impact-position curve for the system.

Itis furthermore to be noted that, although mysystem has been illustrated above as utilizing grid controlled glow tubes; it is equally as well adaptable to be utilized with other types or electric discharge tubes, such as grid-controlled mercury-arc tubes or thermionic tubes.

It is to be noted, however, that grid-controlled glow tubes are abrupt in their action, and consequently, are more suited for a system of the type 5 described hereinabove than ordinary thermionic tubes.

The electrical circuit for the apparatus is illustrated in Fig. 3. In this view, the complete series of impacters 3 are illustrated.

The cathodes 45 of the grid-glow tubes 3 are connected to a common bus line 41 that is, in turn, connected to thenegative terminal 49 of thepower source 5, the preferred form of which is a battery of dry cells, as illustrated. One element 3| of each of the contactors, described and illustrated above, are also connected to the bus line, and hence, to the cathodes 45 of the tubes 3. The remaining element 29 of 'the'contactors are each connected to the control electrode 5| of the tubes 3 through a resistor 53. The control electrode 5| of each tube. 3 is connected to the anode 51' through a second resistor 59 and a capacity 6| of predetermined magnitude, is connected across the two resistors 53 and 59 in each case. The common junction 63 of the leads from the anode'5'l, the capacity 6|, and the resistor 53, isconnected, through a resistor 55 to a bus line 61, which is,

in turn, connected to the positive terminal 59 of the power source 5.

Under ordinary circumstances, the springs IS in the impacters resiliently urge the corresponding masses I! to' close the contacts 29 and 3| and I the corresponding tubes 3 are in an unexcited state. However, under the force of an impulse, 35 certain of the contacts 29 and 3| are opened and the corresponding tubes 3 break down, indicating that the impulse is of a certain magnitude.

When the contacts 23 and 3| are closed, the corresponding capacities 6| are charged and the opening of the contacts causes them to'discharge through the tubes. However, when the contacts are again closed, each uncharged capacity 6| connected across the tube 3 acts as a short circuit for the particular tube and causes it to revert to an 45 unexcited state.

To prevent the battery 5 from being drained when the apparatus is not in use I have included a switch 1| in the battery circuit that is closed when the apparatus is put into use. The switch may or course be positioned in such a manner that it is closed when the door of the chamber is opened or when a male plug is inserted in the female plug I.

Inone type of equipment that I have found useful, tubes "3 of the type requiring an electromotive iorce 5 of 430 volts are utilized. The resistors 53 and 59v that are connected between the control electrodes 5|, and the principal-electrodes 45 and 51 or each tube are each of the order of 25000 ohms. The limiting resistors 65 are of the order of .5 megohm and the capacities 6| are or the orderoi .25 micro-iarad.

described and illustrated hereinabove, my invention has been specifically applied to the detection' and measurement of discontinuous or impulsive forces. It may also be applied to the measurement oi. continuous forces.

In the present connection, I have found that my invention maybe applied to Diesel engines wherein an indication that the pressure has attained a minimum value is of extreme importance.

. apparatus constructed according to my invention vice maybe made of such sensitivity as to respond to sound'pressure. It is thus possible to utilize to measure the reverberation constant of an auditorium.

- In the last-mentioned application, the impacters are disposed in a room in the region where it In the following claims the expression electric discharge tube of arc-like discharge type is used. By this expression I mean a tube having an abrupt characteristic. Such a tube may be regarded as having two conditions-of excitation, a deenergized condition and an energized condition. As the potentials impressed on its electrodes are varied, the tube passes abruptly from one condition to the other. If a tube of this type is provided with a control electrode, it may be energized by varying the control potential, but if it is once energized, it cannot be deenergized by reverting'the control potential ,to a value at which the tube would be deenergized were it .not initially energized. It

I 1. An indicator of the type including a flexibly supported mass associated with a gaseous electric discharge tube of the arc-likedischarge type having principal electrodes and a control electrode,

means for impressing an initial control potential on said control electrode such that said tube is maintained in a predetermined condition of excitation, means, responsive totthe movement of said mass, to vary said initial potential by a predetermined amount such that thecondition of excitation of said tube is changed, and means, responsive to a subsequent movement of said mass such that the potential of said control electrode is varied in a sense opposite to the sense of the last said variation and by at least a predetermined amount to revert the excitation of said tube to its initial condition. v

2. In an indicator of the type including a flexibly supported mass associated with a pair of separable contacts, a gaseous electric discharge tube of the arc-like discharge type having principal electrodes and 'a control electrode, one member of said pair being connected to the control electrode of said tube and to one terminal of a capaci-v tor, the other member of the pair being connected to one principal electrode of said tube and the other principal electrode of the tube being connected to the other terminal of said capacitor.

3. An indicator of the type including a flexibly supported'mass associated with a gaseous electric discharge tube of the arc-like discharge type having principal electrodes and av control electrode and adapted to emit a visual glow, means for rendering the potential of said control electrode responsive to the movement of said means, the last-said means comprising -connec-.- tions for impressing potentials between the control electrode and the principal electrodes of the discharge device such that the discharge device is normally deenergized, and becomes energized when said mass is displaced by an impact and re- 

